The present invention relates to a BGA socket, and especially to a BGA socket having a plurality of standoffs for stably spacing the BGA socket above a mother board and for eliminating wicking of molten solder.
A PGA (Pin Grid Array) socket is commonly used in a computer for providing electrical connection between an IC (Integral circuit) chip and a mother board for electrical connecting an IC chip to a mother board. The PGA socket is usually connected to corresponding pads on the mother board using Through Hole technology. A plurality of through holes is defined through the mother board for allowing corresponding tails of the socket to extend therethrough. However, the through holes occupy space on both sides of the mother board thereby hindering an efficient use thereof.
To absolve the above problem, a BGA (Ball Grid Array) socket is adopted for connection of the IC chip to the mother board. A plurality of solder balls is disposed between tails of the IC chip and electrical pads on the mother board. The solder balls are heated and become molten thereby electrically connecting the tails to the mother board after the molten solder solidifies. The pertinent prior art is disclosed in Taiwan Patent Application Nos. 86,105,336 and 86,100,612.
Referring to FIGS. 1 and 2, a conventional BGA socket 2 comprises an insulative cover 20 and a base 21 attached to a bottom surface of the cover 20. The cover 20 defines a plurality of apertures (not shown) therein. The base 21 defines a plurality of passageways 22 corresponding to the apertures of the cover 20 for retaining corresponding terminals 24 therein. An IC chip (not shown) is attached to a top surface of the cover 20. A plurality of pins of the IC chip extends through the apertures of the cover 20 into the passageways 22 of the base 21 for engaging with the terminals 24. The terminals 24 are electrically connected to a mother board 3 by melting solder balls 210 disposed therebetween. However, the BGA socket 2 does not have a standoff for supporting the BGA socket 2 above the mother board 3. Thus, the solder balls 210 directly sustain the entire weight of the BGA socket 2. During the heating process, the solder balls 210 are unlikely to become synchronously molten whereby a height of the BGA socket 2 above the mother board 3 is difficult to control. Furthermore, a bottom surface of the base 21 may not be parallel to the mother board 3 due to the nonsynchronous melting process of the solder balls 210. The molten solder may upwardly wick into the passageways 22 thereby adversely affecting performance of the terminals 24. Thus, a BGA socket which can absolve the above problems is desired.